This invention relates generally to wind turbine assemblies and, more particularly, to a tower for supporting wind turbine assemblies.
Recently, wind turbine generators have received increased attention as an environmentally safe and relatively inexpensive alternative energy source. With this growing interest, considerable efforts have been made to develop wind turbine generators that are reliable and efficient.
Generally, a wind turbine generator includes a rotor having multiple blades. The rotor is mounted on a housing or nacelle, which is positioned on top of a truss or tubular tower. Utility grade wind turbine generators (i.e., wind turbine generators designed to provide electrical power to a utility grid) can have large rotors (e.g., 30 or more meters in diameter). Blades on these rotors transform wind energy into a rotational torque or force that drives one or more generators rotationally coupled to the rotor.
Many conventional wind turbine assemblies include a tower formed of a single tubular construction, commonly referred to as a “monopole.” Conventional monopoles have been used in the art to provide sufficient clearance for rotor blades to rotate freely without undesirable contact with the tower structure. Further, such monopoles are required to have a height sufficient to facilitate the harnessing of wind energy. Thus, conventional monopoles are custom fabricated of a heavy material, such as steel, having a sufficient thickness and/or a sufficient diameter to support heavy loads and/or forces associated with the wind turbine assembly. This custom fabrication requires many hours of fabrication and a large quantity of material. Further, monopoles are limited in diameter to about 14 feet or 168 inches (4300 mm) due to road transportation barriers, such as bridges that span a highway at a distance of about 14 feet above the road surface.